Protective efficacy of Streptococcus thermophilus against acute cadmium toxicity in mice

Cadmium (Cd) is a highly toxic heavy metal, wide occupational and an environmental pollutant, affecting human health. Probiotics especially lactic acid bacteria (LAB) have the capacity to bind, remove and to decrease tissue cadmium levels. The objective was to evaluate the potency of Cd binding capacity, antioxidative properties of probiotic bacteria against cadmium in vitro and its probable detoxification effect against Cd-induced toxicity in mice. To asses this objective, resistance against cadmium and antioxidative properties (via DPPH radical scavenging and inhibition of lipid peroxidation) were estimated for thirteen probiotic bacteria. Streptococcus thermophilus was selected among investigated bacteria as it had the highest MIC against cadmium and remarkable antioxidant activities for treatment of Cd toxicity in Swiss albino mice by preventive and therapeutic protocols. Blood cadmium levels, reduced glutathione (GSH), malondialdehyde (MDA) and histopathological changes in the liver of mice were estimated at 6, 24 and 48 h post to acute Cd exposure (oral dose with 50 mg/kg body weight). On exposure to Cd a significant increase in blood Cd, MDA and reducing in GSH levels were observed. S. thermophilus offered a significant protective effect against Cd toxicity by decreasing the cadmium levels in blood and attenuation alterations in the levels of GSH and MDA and improved hepatic histopathological changes caused by Cd toxicity. These results indicated the protective action of S. thermophilus against acute cadmium toxicity as well as their beneficial health effects and suggested its use as a safe and efficacious nutritional dietary supplement to reduce cadmium toxicity.